Alpha Tau wins U.S. approval to expand brain cancer trial to 20 patients
Key Facts
Alpha Tau Medical announced on October 19 that the U.S. Food and Drug Administration had approved an expansion of its clinical trial of Alpha DaRT for recurrent glioblastoma. The investigational device exemption supplement raises the enrollment cap in the ReGAIN trial from 10 to 20 patients, according to a company statement. The study primarily aims to assess the treatment's feasibility and safety in patients with this type of recurrent brain cancer. It is an open-label, multicenter, single-arm interventional study. According to the FDA, an investigational device exemption allows a device to be used in a clinical study to collect safety and effectiveness data. Alpha Tau stressed that the technology "has not received approval for commercial marketing," leaving the current approval within the clinical testing process.
The amendments broaden eligibility to include patients with grade 4 tumors carrying mutations in the isocitrate dehydrogenase gene, according to the company. The revised protocol adds progression-free survival to the trial's secondary endpoints. This measure forms part of secondary objectives that also include tumor control, survival and quality of life, alongside the primary assessment of feasibility and safety. The amendment also calls for regular quality-of-life assessments of participating patients during the study. Clinical follow-up thus covers disease progression and patients' experience with treatment, alongside monitoring safety and the feasibility of the technology. According to the company's description of the protocol, the new approval includes changes to eligible patient groups and the measures to be collected during the trial, as well as the higher enrollment cap.
The latest expansion followed FDA approval to resume patient enrollment after the agency reviewed a prespecified interim safety report, according to an earlier Alpha Tau announcement. The company had reported preliminary interim results covering the first 3 patients treated in the U.S. trial. Those results showed complete responses in two patients in the group, according to the company's statement on the preliminary analysis. On safety, the group recorded a grade 3 treatment-related serious adverse event. Alpha Tau said the event subsequently resolved, as part of its presentation of safety results for the patients included in the analysis. The regulatory decision to resume enrollment followed the safety report review, preceding the latest approval broadening participation and amending the follow-up protocol.
The study targeted patients with recurrent glioblastoma that could not be surgically removed, according to the company's description of the patient population. These patients had previously received a course of radiation therapy to the central nervous system, under the study's stated criteria. As medical background to this approach, the U.S. National Cancer Institute says cures are rare in patients with recurrent central nervous system tumors. The institute recommends considering enrollment in clinical trials for these patients. Alpha Tau announced on December 9, 2025, that the first patient had been treated in its U.S. trial for recurrent glioblastoma. The treatment was administered at Ohio State University's James Cancer Hospital, according to the company's announcement on the start of treatment for study participants.
Alpha DaRT uses radium-224 to deliver localized alpha-particle radiation therapy inside the tumor, according to Alpha Tau's explanation of how the technology works. The company describes the isotope as suitable for localized treatment within tumors using alpha particles. These particles have high linear energy transfer, allowing concentrated energy to be deposited over a very short distance, according to the company. On the regulatory front, the technology received FDA breakthrough device designation for recurrent glioblastoma in October 2021. The company was then accepted into the agency's Total Product Life Cycle Advisory Program pilot in October 2024. The expansion of the U.S. trial is part of this process, combining the study of clinical application, safety monitoring and treatment data collection.
Financially, Alpha Tau held $104.8 million in cash, cash equivalents, short-term deposits and restricted deposits as of June 30, 2026, according to its financial results. In its next scientific step, the company plans to present new data from the ReGAIN trial at the Society for Neuro-Oncology's annual meeting in Philadelphia. It said the presentation accepted for the meeting would supplement the previous interim results with new trial data. The meeting runs from November 12 to 15, 2026, according to the dates in the company's announcement. The revised protocol also includes an additional interim analysis 6 months after treatment of the fifth patient. Alpha Tau said that patient was treated in July 2026, the date that determines the timing of the planned additional analysis.